This invention relates to self closing hinges and in particular, to a new and improved spring for a self closing hinge, which spring is a unitary item, typically molded of a resilient plastic, which may be directly substituted for other spring designs now being used.
Several types of self closing hinges are presently on the market. In one design, a small injection molded part is placed between the hinge knuckle and the door wing of the hinge. Two compression springs are positioned within the small plastic part. One surface of this part is contoured to effect a ramp or bevel or step. This ramp surface bears against the hinge knuckle, and the opposing surface is held in position by a portion of the door wing. The hinge knuckle has a void in its circumference that matches the dimensions of the plastic insert.
In operation of such a hinge, when the hinge wing is pulled outward to open, the leading edge of the knuckle adjoining the void engages the ramp and compresses the two springs within the plastic part. Since there is now an interference with the knuckle surface and the ramp, the door stays open and typically at a position of 30-35 degrees from a closed position. There is no further increased interference on the contact point between the knuckle and the ramp so the door can open for full access. Upon closing, the ramp of the plastic part disengages from the knuckle at the point where the void begins. This in turn causes the door to self close.
Another self closing design utilizes a spring incorporated around the hinge pin, with the ends of the spring extended and in contact with the hinge wings or its housing. When the hinge is activated, these extended ends produce tension within the spring thereby providing the self closing or return feature.